Monitoring of the central venous pressure is a simple, relatively inexpensive method of assessing a patient's cardiac status, circulating blood volume, and vasomotor tone. The simplest way of checking the intrathoraeic location of the catheter tip is by observing oscillation of 2~4cmH2O in the manometer column, synchronous with respiratory cycle. Inaccurate measurements are often obtained by the misplacement of the central venous catheter tip, in addition to the other well-known complications. Radiographic identification of the catheter tip is essential to eliminate these problems. We experienced a case of arrhythmia which appeared upon misplacement of the central venous catheter tip, and confirmed its misplacement by radiographic study.